1. Field of the Invention
The present invention relates to a metering pump for dispensing fluid, liquid or pasty products, and more particularly to a manually actuated metering pump for a rigid bottle having a flexible pouch or a piston and dip tube, containing a fluid, liquid or pasty product intended to be delivered in constant individual doses, and to a dispensing device equipped with such a pump.
2. Description of the Related Art
The operating principle of metering pumps for dispensing fluid, liquid or pasty products is well known. These pumps are mounted on a bottle containing the product to be dispensed and are formed from a metering chamber of defined volume, a piston capable of moving in the chamber under the action of a pusher, and at least two valves. The lower valve, or intake valve, located at the inlet of the chamber and controlling the communication with the inside of the bottle, is closed when the pusher is pushed right in, while the lower valve, at the outlet of the chamber, is open, allowing the product expelled from the chamber by the displacement of the piston to pass, and then, when the pusher is released, the piston rises back up in the chamber under the action of a spring, the upper valve closes, while the lower valve opens, making it possible to fill the chamber for the purpose of dispensing a new dose of product.
This mode of operation means that air can be introduced into the bottle to make up for the volume released by the product expelled from the bottle and can allow the metering chamber to be uniformly filled at each actuation of the pusher.
To package and dispense products that have to be kept away from air, especially in the field of pharmaceutical and cosmetic products, devices are known that generally comprise a container with a rigid shell in which a piston moves, said piston pushing the product toward the inlet orifice in the metering chamber and isolating it from the air that penetrates above the piston. Also known are devices with a rigid container in which a flexible pouch is placed, said pouch retracting progressively as the product is extracted therefrom. The product remaining in the pouch is kept away from air, whereas the expulsion of the product out of the pouch can be achieved by means of an airless pump, or under the pressure of a propellant gas that acts on the wall of the pouch, inside the bottle.
In the case of expulsion of the product from the pouch by means of an airless pump, a vent is provided, generally in the bottom or in the neck of the bottle, in order to allow external air to enter into the space lying between the bottle and the pouch at each actuation of the pump, and thus to allow the pouch to retract while maintaining sufficient pressure on its walls. One illustrative example according to this technique is disclosed in patent FR 2 723 356 relating to a device that includes a flexible plastic pouch, such as one made of polyethylene or polypropylene, in a rigid container whose neck includes an air inlet.
The pumps must provide good sealing and be able to operate both in a vertical position and in an inclined position. Patent FR 2 669 379 discloses a metering pump that ensures good sealing even in the situation when there is a change of position, of the type with an axial piston, carrying a sliding floating piston, having three valves. Patent FR 2 726 810 discloses an example of an airless pump in which the lower valve is flexible and frustoconical, while the upper valve is carried by a disk placed at the base of the hollow stem of the pusher. However, pumps of this type have the drawback of comprising a relatively large number of components, which weakens them and increases their manufacturing cost.
Patent EP 0 538 162 discloses a closure device for a bottle, one variant of which includes a hollow pusher forming a metering chamber, between an output valve and an intake valve; when the pusher is actuated, the base of the part forming the lower valve is pushed back and deforms, therefore making it easier for the truncated cone surrounding the axial cylindrical part to open, which runs the risk of causing fluid to return into the bottle. Patent application WO 95/25945 relates to a pump that includes a deformable lower valve and an expulsion valve, the orifice of which is similar, but the dimensions and the functions of which are different. Other examples of dispensing bottles with a hollow pusher are disclosed in patents EP 888 823 and EP 733 559. In all these dispensing bottles, the valves have different shapes, dimensions and functions.